This code warns that the derived class hides a virtual function -- except that it doesn't:

  struct Base {
    virtual void foo(int);
  };
  
  void Base::foo(int) { }
  
  struct Derived : public Base {
    virtual void foo(int);   
    void foo(int, int);   
  };

note that if you move the out-of-line Base::foo def'n after struct Derived, then it doesn't warn any more. Here's the clang output:

  $ clang++ -c x.cc -Woverloaded-virtual 
  x.cc:9:8: warning: 'Derived::foo' hides overloaded virtual function
        [-Woverloaded-virtual]
    void foo(int, int);
         ^
  x.cc:5:12: note: hidden overloaded virtual function 'Base::foo' declared here
  void Base::foo(int) { }
             ^
  1 warning generated.